Spark plug



Sept.' l, 1925.

E. w. SHEPHERD SPARK PLUG Filed Aug. l1, 1921 Patented Sept. 1, 1925.

UNITED STATES EDWARD W. SHEPHERD, 0F NEW LONDON, CONNECTICUT.

SPARK PLUG.

Application led August 11, 1921.

To zZ/f whom it may concern:

Be it known that I, EDWARD V. SHEPHERD, a citizen of the United States, residing in New London, in the county of New London and State of Connecticut, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

This invention relates to a spark plug wherein the pressure of explosion and compression within the engine cylinder .has a cleaning effect upon the sparking points and operates to remove accumulations of carbon from the sparking points and the cylinder.

One object ofthe invention is to improve generally the simplicity and efficiency of such devices and to provide a device of this kind in which the flow of the exuded carbon deposit is so constricted as to prevent any lowering of the pressures within the cylinder.

v Another object of the invention is to provide easily renewablesparking points, and sparking points so designed as to direct the moving gases in a manner to effect thorough cleaning of the sparking surfaces.

To the above ends, I have provided -a spark plug having a metallic outer jacket or base having an intermediate annular recess forming an expansion chamber communicating with the outside air, in which base there is received a removable metallic inner jacket co-operating with said recess to form an expansion chamber, and having a return ignition end so shaped as to direct the gases against the axial electrode of the spark plug.

A helical groove is provided for establishing said expansionV communication between chamber and the interior of the lower part of the inner jacket.

Another object of the invention is to pro-1 vide an eiiicient spark plug which is easily.

Serial No. 491,53?.

Fig. 2 is a side elevation of the same;

Fig. 3 is an axial sectionalview on the outer jacket or base of the spark plug;

Fig. 4 is a sectional view of the inner jacket;

Fig. 5 is a sectional view of the gland or bushing. I

Fig. 6 is a side elevation of the inner jacket; v

Fig. 7 is a bottom view of the sparking end of the inner jacket; and

Fig. 8 is a helical sectional view at the helical groove of the lower part of the inner jacket.

My improved spark plug comprises a metallic outer jacket or base 10 having a reduced and exteriorly threaded lower end portion 11 for the insertion into the spark plug receiving opening of an engine cylinder (not shown). Said jacket or base 10 has an enlarged hexagonal interiorly threaded upper portion 14, a shouldered annular interior expansion chamber recess 15 disposed between the interior threads and the interior of the lower reduced portion, and a lateral perforation 16 communicating with said recess just at its upper juncture with the interior threads.

A removable metallic inner jacket 18 having an interior outerjacket-engaging top flange 19, and an interiorly and exteriorly threaded outer-j acket-engaging enlarged upper lportion 20, has an inclined interior shoulder 21, and an intermediate annular exterior shoulder 22 co-operating with said annular recess to form an intermediate expansion chamber. The hollow cylindrical lower reduced portion 24 of said inner jacket terminates in a perforated centrally open cone-shaped end wall 25, forming a return ignition edge 26. Said reduced portion 24 fits into the reduced portion 11 of the outer jacket and is provided with an exterior spiral groove 27 extending to said expansion chamber. Holes 28 establish communication between said spiral groove 27 and the interior of the reduced portion 24 of the inner jacket. i c

A mica or porcelain insulator 30 disposed in said inner jacket terminates at lits lower end, a distance from said end wallproviding a chambered space in the inner jacket between the lower end of the insulator and said end wall, and has an intermediate annular enlargement 31 disposed in the interrior of lthe upper part of the inner jacket and having inclined upper and lower faces 33 receiving packings 34 and 35, the latter of which is engaged by a bushing lor gland 36 in threaded engagement in the upper part of said innerjacket and pressing said packings 34 and 35, said enlargement 3l, and inclined shoulder 21 into gas-tight engagement with each other, An electrode or terminal rod 38 having binding means 39 at the upper part passes axially through said insulator 80 and forms an ignition terminal 40 slightly projecting from the opening of the end wall and spaced from said sparking edge 26.

The operation of the device is simple and obvious. The spark plug being assembled as in Fig. l and inserted in the cylinder, sparking takes place between the edge 26 and the end 40. The pressures of compression and explosion cause a flow of gases through the o-penings in the end wall 25 past the terminal Ll() and edge 26, thus cleaning these parts and carrying the depositinto the interior or chambered space of the lower part 24 of the inner shell and thence through the holes 28, the groove 27, the expansion recess 15 and perforations 16, where the deposit and fuel residue mixture, due to the retardation thereof vin passing through the tortuous or helical channel 27oozes out, the retardation caused by the channel 27 pre venting 4as well the too rapid outflow of the gases from the spark plug and consequent lowering of pressure in the engine cylinder.

I claim as my invention:

l. A spark plug for internal combustion cylinders, having an electrode therein; and means for providing passage of explosion fluids 'around' the ignition end of the electrode andi througn the spark plug to the atmosphere; said means comprising a tortu- .ouS .channel for retarding the flow of the explosio fluids during said passage.

" 2,l A spark plug for internal combustion cylinders, having anV electrode therein; and

in'eans'for providing passage of explosion fluids aro-und the ignition end of the electrode and through the spark plug to the atmosphere; said means comprising' a helical channel for retarding the flow of the explosion fluids during said passage sufficiently to prevent excessive lowering of the pressure inthe cylinder.

3. A spark plugfor internal combustion cylinders, having an operatively arranged electrode therein; and means for providing passage of explosion fluids around the ignition end of the electrode and through the spark plug to the atmosphere; said means comprisinga channel suliiciently, long for retarding the flow of the explosion uids during said passage sufliciently to prevent excessive lowering of the pressure in the cylinder.

4 A spark plug for internal combustion cylinders, having an operatively arranged electrode therein; and means for providing passage of explosion fluids around the igni tion endoftheelectrode-and through the spark plug to the atmosphere; said means comprising a channel for retarding the flow of the explosion fluids during said passage sufficiently to prevent excessive lowering of the pressure in the cylinder; said channel being several times longer than the distance from the inner end of the spark plug to the exterior of the cylinder.

5. A spark plug for internal combustion cylinders, having an operatively arranged electrode therein; and means for providing passage of explosion gases aroundl the ignition end of the electrode and through the spark plug to the atmosphere; said means comprising a permanently open channel adapted to retard the flow of the explosion gases during said passage without excessive lowering ofthe pressure in the cylinder.

6. A spark plug for internal combustion cylinders, having an electrodetherein; and means for providing passage of. explosion fluids around the ignition end' of the electrode to the atmosphere; said means comprising a tortuous channel exerting suflicient friction on the fluids to retard the flow 4of the fluids during said passage sufficiently to prevent excessive'lowering of the pressure in the engine cylinder.

7. A spark plug for internal combustion cylinders, having an operatively arranged' electrode therein; andv means for providing passage of explosion gases around the ignition end of the electrode and through the snark plug to the atmosphere; said means comprising a channel having a plurality of inlets and adapted to retard the flow of the explosion gases during'said passage'without excessive lowering of the pressure inthe cylinder. Y

8'. A spark plug for internalcombustion cylinders, having an operatively arranged electrode therein; and means having a single outlet providing passage of explosion fluids around the ignition end of the electrode and through the spark plug to the atmosphere; said means comprising a channel having aplurality of inlets andfexerting sufiicient friction on the fluids to retard the flow ofthe fluids during said passage sufliciently to prevent excessive lowering of the pressure in the cylinder.

9.r An internal combustion cylinder spark plug having an electrode therein andcomprising a pair of parts cooperating'to form means for providing passage offexplosion fluids around the ignition end' of thegel'ectrodeand through the spark plug to the atmosphere; said means comprising a tortuous channel exerting friction on the fluids lto retard the flow of the ilu-ids during said' passage sufficiently to prevent excessive lower ing of the pressure in the engine cylinder; each of said parts forming a portion of said channel substantially from end to end thereof.

10. A spark plug comprising an outer jacket having a lateral perforation; an inner jacket in the outer jacket cooperating therewith to form a passage communicating with said perforations; a portion of said inner jacket having its exterior face provided with a groove to form a channel communicating with said passage and space; and an electrode passing through said insulator and projecting and spaced from` said end wall.

1l. An `internal combustion engine spark plug having an electrode therein and comprising a pair of parts cooperating to form means for providing passage of explosion fluids around the ignition end of the electrode and through the spark plug to the atmosphere; said means comprising an annular chamber communicating with the atmosphere and a tortuous channel exerting friction on the fluids to retard the flow of the fluids during said passage; each of said parts forming a portion of said chamber substantially throughout.

12. An internal combustion engine plug having an electrode therein and comprising a pair of parts cooperating to form means for providing passage of explosion fluids around the ignition end of the electrode and through the spark plug to the atmosphere; said means Acomprising an expansion chamber and a tortuous channel exerting friction on the fluids to retard the How of the fluids; each of said-parts forming a portion of said channel and chamber substantially from end to end thereof.

13. In combination, an outer jacket having lateral perforations; an inner jacket in the outer jacket cooperating therewith to form an expansion chamber communicating with said perforations; an insulator in said inner jacket Aleaving a chambered space at the lower end portion; the lower end portion ot' said inner jacket terminating in an end wall having a central opening, said inner jacket having its exterior face provided with a groove to form a channel communicating with said chamber and said space; and an electrode passing through said insulator and projecting and spaced from said end wall.

14. In combination, with the cylinder of an internal combustion engine, a spark plug having an operatively arranged electrode therein; and means for providing passage of explosion gases from the engine cylinder around the ignition end of the electrode and through the spark plug to the atmosphere; said means comprising a tortuous channel for retarding the iow of the ex-.

plosion gases during said passage for preventing 'lowering of pressure in the engine cylinder.

15. In combination, an outer jacket having an intermediate annular recess and lateral perforations communicating with the recess; an inner jacket fitting in the outer jacket and co-operating with said recess to form an expansion chamber, and having its lower end portion terminating in a perforated centrally openend wall, and having its lower exterior face provided with a groove communicating with said chamber and the interior of the inner jacket; an insulator in said inner acket and terminating a distance from said wall; and an electrode passing through said insulator and slightly projecting and spaced from said end wall.

16. In combination, a metallic outer jacket having a reduced and exteriorly threaded lower end portion, anv enlarged interiorly threaded upper portion, an annular interior expansion chamber recess disposed between the interior threads and the interior of the lower reduced portion, and lateral perforations communicating with said recess; a metallic inner jacket having a jacket-engaging top flange, an interiorly and exteriorly threaded enlarged upper portion, an intermediate face portion co-operating with said annular recess to form an intermediate expansion chamber, and a hollow lower re-v duced portion terminating in a perforated centrally open end wall, and fitting into said reduced portion of the outer jacket and provided with an exterior helical groove extending to said chamber, and holes establishingcommunication between said groove and the interior of the inner jacket; an insulator' disposed in said inner jacket; and an electrode passing axially through said insulator and slightly projecting and spaced from said end wall.

EDIVARI) YV. SHEPHERD. 

